Generally, in a semiconductor manufacturing process, a circuit pattern is formed, for example, by applying photoresist onto a substrate such as a semiconductor wafer, exposing and developing the resist film according to a predetermined circuit pattern. In a photolithography process as the semiconductor manufacturing process, a processing system having an exposure apparatus connected to a coating and development processing apparatus is generally used.
In the processing system, a substrate is taken out one by one from a cassette transferred by an overhead hoist transfer (OHT) cassette transfer mechanism, and is processed in a processing unit of a processing part, and then, the substrate after being processed is returned into the cassette. In such a case, a highly airtight cassette referred to as a FOUP (front opening universal pod) is used, a cassette main body is provided with an opening for charging and discharging a substrate, and the opening is provided with a lid that can be locked by a latch mechanism.
In the processing system, the cassette transferred by the cassette transfer mechanism is mounted onto a cassette mounting table installed in the processing system, and the lid of the cassette is unlocked and opened by a lid attaching/detaching mechanism having a key installed in the processing system. In a state where the lid is opened, a substrate is taken out from the cassette with the lid opened by a substrate transfer mechanism disposed in the processing system and is transferred to the processing unit of the processing part, and processing steps such as photoresist coating and developing is performed in the processing unit. Thereafter, the processed substrate is returned to the cassette by the substrate transfer mechanism. Then, the lid is closed and locked by the lid attaching/detaching mechanism. The cassette with the lid closed is unloaded from the cassette mounting table by the cassette transfer mechanism and is transferred to a transfer path, a cassette receiving part or the like that is formed in an outer upper portion of the processing system.
However, if the lid is insufficiently locked after the processed substrate is accommodated into the cassette, there is a risk that vibration or the like during the transfer of the cassette causes the lid to be opened, causing the substrate in the cassette to fall, or the lid to be partially opened, causing the substrate in the cassette to protrude to the outside.